I'm using Merlin atm, so the command below will work.
ssh router-admin-name@router-ip service stop_vpnclient1
ssh router-admin-name@router-ip service start_vpnclient1
You will need to turn off allow password login and generate/add the keys from your machine.
But it works well. I will write up a full guide, only took me about a day to figure out so it can't be that hard.